78 lines
2.4 KiB
Rust
78 lines
2.4 KiB
Rust
///! This example registers a variety of functions that operate on strings.
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///! Remember to use `ImmutableString` or `&str` instead of `String` as parameters.
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use rhai::{Engine, EvalAltResult, ImmutableString, RegisterFn, Scope, INT};
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use std::io::{stdin, stdout, Write};
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/// Trim whitespace from a string. The original string argument is changed.
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///
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/// This version uses `&mut ImmutableString`
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fn trim_string(s: &mut ImmutableString) {
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*s = s.trim().into();
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}
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/// Notice this is different from the built-in Rhai 'len' function for strings
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/// which counts the actual number of Unicode _characters_ in a string.
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/// This version simply counts the number of _bytes_ in the UTF-8 representation.
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///
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/// This version uses `&str`.
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fn count_string_bytes(s: &str) -> INT {
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s.len() as INT
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}
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/// This version uses `ImmutableString` and `&str`.
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fn find_substring(s: ImmutableString, sub: &str) -> INT {
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s.as_str().find(sub).map(|x| x as INT).unwrap_or(-1)
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}
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fn main() -> Result<(), Box<EvalAltResult>> {
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// Create a `raw` Engine with no built-in string functions.
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let mut engine = Engine::new_raw();
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// Register string functions
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engine.register_fn("trim", trim_string);
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engine.register_fn("len", count_string_bytes);
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engine.register_fn("index_of", find_substring);
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// Register string functions using closures
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engine.register_fn("display", |label: &str, x: INT| {
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println!("{}: {}", label, x)
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});
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engine.register_fn("display", |label: ImmutableString, x: &str| {
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println!(r#"{}: "{}""#, label, x) // Quote the input string
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});
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let mut scope = Scope::new();
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let mut input = String::new();
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loop {
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scope.clear();
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println!("Type something. Press Ctrl-C to exit.");
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print!("strings> ");
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stdout().flush().expect("couldn't flush stdout");
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input.clear();
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if let Err(err) = stdin().read_line(&mut input) {
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panic!("input error: {}", err);
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}
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scope.push("x", input.clone());
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println!("Line: {}", input.replace('\r', "\\r").replace('\n', "\\n"));
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engine.consume_with_scope(
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&mut scope,
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r#"
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display("Length", x.len());
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x.trim();
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display("Trimmed", x);
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display("Trimmed Length", x.len());
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display("Index of \"!!!\"", x.index_of("!!!"));
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"#,
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)?;
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println!();
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}
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}
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